In the sector of dentistry computed tomography scanners are used, in the present state of the art, of the type comprising an x-ray source-detector assembly designed to rotate about an area of analysis in which the head of a patient is positioned for acquiring volumetric tomographic data of one or both of the dental arches of the patient. The source-detector assembly comprises a rotating support, typically constituted by an arm that is motor-driven so as to rotate about a horizontal axis traversing said area of analysis, an x-ray emitter, mounted on a first end of the arm for emitting an x-ray beam through the area of analysis, and an x-ray detector, mounted on the opposite end of the arm and facing the emitter for receiving the beam after it has traversed the area of analysis.
The tomography scanner 1 further comprises a control unit, connected to the source-detector assembly for controlling emission and reception of the beam in a way synchronous with rotation of the arm, and a processing unit connected to the detector for receiving, storing, and processing the volumetric tomographic data so as to reconstruct images of the object.
In particular, the control unit generates a first signal for operating the detector for a given exposure time, and a second signal for operating the emitter so that it emits an x-ray beam only after the detector has been operated to prevent useless doses of x-rays from being administered to the patient. The two signals for operation, respectively, of the detector and of the emitter are generated starting from a single pre-defined synchronisation signal, generated by the control unit, for example as a function of the angular position of the arm.
The fact of having a number of units, i.e., the emitter and the detector, controlled according to a single synchronisation signal generated by a control unit, gives rise to latency times due to the propagation of the synchronisation signal along the connections between the control unit and the various controlled units, said latency times not always being predictable and being of the order of magnitude of the times involved, i.e., of the order of magnitude of a few microseconds or of some tens of microseconds. Said latency times generate synchronisation errors between the controlled units.